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Biomedical subjects

C Ropartz

Publications and source records attributed to C Ropartz.

At least 19 recordsLinked to original sources
PubMed1989

[Preventive treatment of infection caused by gram-negative bacteria using anti-lipopolysaccharide antibodies. Evaluation in patients with aplasia].

The prophylaxis of severe Gram-negative infections with human antiserum to lipopolysaccharide (LPS) was evaluated in a randomised study of 60 patients with therapeutic aplasia for leukaemia. The antiserum was found to be ineffective in preventing Gram-negative infections. The levels of anti-LPS antibodies showed that passive immunization was obtained in only one half of the patients. These disappointing results warrant further investigations to evaluate the effectiveness of this prophylactic treatment.

Adult↗
PubMed1978

Common and uncommon immunoglobulin haplotypes among Lebanese communities.

Allotypes of IgG1, IgG2, IgG3, and IgA2 subclasses were investigated in seven Lebanese communities (three Moslem and four Christian). The Gm-Am haplotypes found were mainly those prevalent in Caucasians with a low frequency of haplotypes usually observed in Africans and Orientals. The difference between highlanders and lowlanders as expressed by G2m(23) was highly significant and suggested a possible adaptation to selective pressure related to the gamma2 genes, possibly due to endemic malaria in the past. Exceptional Gm-Am haplotypes were unambiguously determined by family studies. Some were characterized either by a deletion or a repression or, in contrast, by a partial or total duplication of gamma genes. Two others had uncommon combinations of allotypes: Gm17;23;5,10,11,13,14 A2m1, where G1m (17) was present without G1m (1); and Gm3;23;5,14 A2m1, where the CH3 allotypes G3m (10,11,13) were lacking.

Gene Frequency↗
PubMed1978

[Study of a population carrying HLA B27 antigen compared with a population without B27, in the detection of ankylosing spondylitis].

Comparative study of 2 groups matched for age and sex, 39 subjects with B 27 and 40 subjects without B 27, chosen at random from blood donors, leads to the conclusion that the former complain of chronic low back pain and joint manifestations, and show a reduction in the range of movement of the lumbar spine, significantly more frequently than the latter. While radiological abnormalities of the sacro-iliac joints considered individually do not permit separation of those bearing the antigen from the controle, grouping them together shows that there are more cases of stage III sacro-ilitis among those with B 27. In all, 5 cases of spondylitis defined according to the New York criteria were found in this way in the group with B 27, 12.8 per cent as against 3 per cent in the controls. From these results, the incidence of rheumatic spondylitis can be estimated as between 0.8 and 1.7 per cent.

Adult↗
PubMed1977

IgG4 subclass in malignant melanoma.

Three hundred and ninety-seven sera from 185 melanoma patients were studied. These sera were classified into three groups according to stage of disease. An alteration in the level of the IgG4 subclass was found. It was related to the dissemination of disease. The percentage of abnormalities (either increased or decreased levels of IgG4) was more frequent in patients with stage II and III diseases (55 and 53%, respectively) than in patients with stage I(19%). The higher frequencies of high titers of IgG4 were essentially detected in advanced disease. The biologic significance of the increase of IgG4 in melanoma remains obscure. The increase may be related to the development of facilitating antibodies of the IgG4 subclass.

Female↗
PubMed1977

Recombination, mutation, or constitutive expression at a Gm locus and familial hypergammaglobulinemia.

In a hypercholesterolemic Lebanese family, an uncommon Gm haplotype carrying an unexpected C gamma 1 gene was inherited by only one of 10 siblings. A new recombination during the maternal or paternal meiosis could explain its formation. According to this hypothesis, our data would be informative for the linkage relationship between the gamma-cistrons and the alpha 2-cistron. The latter might be located near the N-terminal side of the gamma-cistron linkage group, and the sequence of genes would be alpha 2, gamma 4, gamma 3, and gamma 1. A mutation could also effect the change from G1m(17) (codons AAA and AAG) TO G1m(3) (codons AGA and AGG). Another alternative is to postulate a constitutive expression of a C gamma 1 structural gene which, normally, would not be expressed. The uncommon derepression could be the consequence of uncommon cellular response to environmental, pathological or metabolic perturbation of a regulatory mechanism.

Adolescent↗
PubMed1976

Localization of J-chain and interchain disulfide bonds in a human F(c)5mu-like fragment.

The inter H-H cysteinyl peptides and the localization of the J-chain were studied in a human F(c)5mu-like fragment. The latter was found to be built up by non-covalent association of molecular forms of 140 000, 95 000 and 70 000 dalton subunits. The trimeric, dimeric and monomeric forms were obtained from gradual reduction by dithiothreitol of the major component of 140 000 daltons, thus confirming the tetrameric nature of this subunit. The latter was found to result from the association of both components of the 70 000 dalton subunit, with the participation of the inter H-H subunit bridge. Structural analysis of the labelled peptides obtained by partial reduction and alkylation showed the presence of the intersubunit disulfide bridge and of the inter heavy-heavy chain bridge of the C-terminal region, and the absence of the heavy-heavy chain bridge of the hinge region. The sequence of these peptides is identical to the sequences of the corresponding peptides of normal mmu-chains. The J-chain, which was covalently linked to this F(c)5mu-like fragment, was found to be predominantly associated within the 95 000 dalton subunit. The results showed that the J-chain was linked in the protein as a "clasp" within a single subunit and not between two subunits.

Amino Acid Sequence↗
PubMed1976

Deletion of hinge region of human myeloma IgG1 molecule (protein LEC) associated with nonexpression of G1m (3) and Km (1, 2) allotypes. A possible genetic explanation at the DNA level.

In this paper we report the structural basis for the nonexpression of G1m(3) and Km (1,2) allotypes in an IgG1 (kappa) human myeloma protein (protein LEC). Heavy and light chains spontaneously dissociate in sodium dodecyl sulfate polyacrylamide gels. Light chains appear to be covalently S-S bonded. Analysis of cysteine-containing peptides shows that the heavy chain of the IgG protein LEC has a deletion of residues 216-230, thus encompassing the entire hinge region. An arginine residue, characteristic of the G1m(3) marker is present at position 214. An alanine at position 153 and a leucine at position 191 of the light chain, characteristic of the Km (1, 2) allotypes, are present. It is likely that the double Km and Gm lack of expression is the result of the deletion. The genetic implications of the sequence of this protein are discussed.

Amino Acid Sequence↗
PubMed1976

Antigenic determinants of heavy chain variable regions: immumological typing of the human immunoglobulin VHIII subgroup.

An antigenic determinant of the VHIII variable region subgroup was defined by means of a heterologous specific antiserum using a hemagglutination inhibition procedure. The specificity of this antiserum was established in inhibition experiments with proteins either of known primary structure or belonging to a definite VH subgroup. A series of IgG, IgA, IgM and IgD monoclonal proteins was examined for the presence of this VHIII subgroup antigenic determinant. The data showed that 50% of the IgG, 62% of the IgA, 55% of the IgM and 41% of the IgD were VHIII-positive, and that certain "blocked" monoclonal immunoglobulins belonged to this subgroup. A preferential association of the VHIII antigenic determinant with the IgG1 and IgG3 subclasses was observed among IgG myeloma proteins while the preferential association was only observed with the IgG1 subclass when anti-Rh antibodies were studied. The VHIII subgroup exhibited nonallelic behavior.

Epitopes↗
PubMed1976

Quantitative studies of Gm allotypes. I. Reappraisal of the method using an autoanalyzer.

In this study, various parameters for the autoanalyzer hemagglutination-inhibition circuit applied to Gm studies, were examined. Details are given of modifications of this circiut and related methodology, that improve its precision and the reproducibility of results: use of a cells counter, effects of temperature, PVP, Tween 20, anti-Gm concentration, etc. The effects of age, storage and freezing on quantitative Gm allotypes antigenicity are also stressed.

Antibodies, Anti-Idiotypic↗
PubMed1976

Expression of genetic markers of erythrocyte immunoglobulin G autoantibodies in autoimmune hemolytic anemia.

The Gm allotype constitution of the autoantibody molecules and the serum Gm phenotypes were determined in 19 patients with autiommune hemolytic anemia of IgG type. The results showed that the known heterogeneity of the antierythrocyte autoantibodies in this disease concerns not only the immunoglobulin class and the isotypic subclass, but also the genetic markers of these molecules. Evidence was obtained that the anomalous production of antierythrocyte autoantibodies is polyclonal, that thse autoantibodies belong mainly to the IgG1 isotypic subclass, and that they have a preference for the Gm(1) allotype. In addition, certain of the findings point to a preferential expression of the Gm(1,21) haplotype.

Anemia, Hemolytic, Autoimmune↗
PubMed1976

Genetic variants of serum alpha1-antitrypsin (Pi types) in Portuguese.

The results of Pi typing on 330 Portuguese from the area of Lisbon are reported. We found six phenotypes and four alleles out of the 24 described in the literature. The allele PiM is the most frequent as in other populations, PiS shows a high frequency (0.1152), and PiF is absent, which agrees satisfactorily with former studies carried out in Spain. These results are compared with others and the entity of the Iberian population is evoked.

Female↗
PubMed1976

[Rheumatic manifestations in 80 cases of Crohn's disease].

Out of a series of 80 patients suffering from Crohn's disease, 31 presented rheumatic manifestations. In 16 subjects this took the form of synovitis closely dependent on the enteritic evolution, which developed after the alimentary symptoms, and which worsened as they did and sometimes regressed as they did following medical or surgical treatment. In combination with erythema nodosum, aphtosis, and conjunctivitis, synovitis appears to be the expression of an immune response to the enteritic lesion. Three cases of chronic polyarthitis and 6 cases of asymptomatic sacro-ileitis were also observed, and 6 cases of spondylarthritis of a minor radiological type were observed that evolved independently of the Crohn's disease. Typing according to the HLA system using 26 antigens was carried out in 44 subjects; no difference in phenotype frequency was found between a control group (blood donors) and the group of subjects with Crohn's disease alone; however, the antigen W 17 was found significantly more frequently in those subjects with peripheral arthritis and the antigen W 27 was found more frequently in those with spondylarthritis. These findings suggest, although it is not certain, the existence of genetic susceptibility to rheumatic manifestations in certain sites in patients with Crohn's disease.

Arthritis↗